This project investigates the pathophysiology of retinoic acid action in vivo. Rats are the current model, but expansion into mouse and guinea pig models is anticipated. The primary focus of the rat model is the pharmacokinetic assay of the interaction of 13-cis-retinoic acid with neuroleptics. Early results have shown statistically significant changes in the blood levels of haloperidol and one of its metabolites after the concurrent administration of 13-cis-retinoic acid to rats. Early results also suggest possible interactions with dopamine metabolism and opiate levels in the central nervous system.